Yup, I have
In many places Al-Anon and ACoA have merged. You will find very few, if any, ACoA meetings, but instead find meetings in the Al-anon directory listed as being "AC".
Other places the two programs are still separate.
ACoA meetings follow the ACoA "Red Book".
Al-anon / AC use various books and pamphlets that Al-anon publishes for ACoA's, along with the "Red Book".
Other than the available literature, I have not found much difference. The folks that attend both kinds of meetings come from the same background. It's just more practical for the two programs to work together since there is so much overlap.
Mike